<template>
  <div>
    <h2>当前求和为：{{ sum }}</h2>
    <select v-model.number="n">
      <option value="1">1</option>
      <option value="2">2</option>
      <option value="3">3</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script>
  export default {
    name: "Count",
    data() {
      return {
        sum: 0, // 当前的和
        n: 1, // 用户选择的数字
      };
    },
    methods: {
      increment() {
        this.sum += this.n;
      },
      decrement() {
        this.sum -= this.n;
      },
      incrementOdd() {
        if (this.sum % 2) {
          this.sum += this.n;
        }
      },
      incrementWait() {
        setTimeout(() => {
          this.sum += this.n;
        }, 500);
      },
    },
  };
</script>

<style>
    button {
        margin-left: 5px;
    }
</style>